Shrink tubing jacket construction, and method

ABSTRACT

A shrink tubing jacket construction enables blade-free or enhanced removal of shrink tubing from an underlying substrate, such as a catheter construction. The shrink tubing jacket construction comprises a length of shrink tubing and one or more tear members located within the wall of the shrink tubing. The wall of the shrink tubing has a certain first material strength and the tear member has a certain second material strength, such that when the tear member is in tension, the second material strength functions to slice through the wall of the shrink tubing for enabling blade-free removal of the same. Paired tear members may be diametrically opposed such that when simultaneously tensioned in a diametrical direction, the net stress on the underlying substrate is minimized during the slicing action.

PRIOR HISTORY

This non-provisional patent application claims the benefit of U.S. Provisional Patent Application No. 60/839,991, filed in the United States Patent and Trademark Office on Aug. 24, 2006.

BACKGROUND OF THE INVENTION

2. Field of the Invention

The disclosed invention generally relates to a thermal plastic tubing construction or heat-shrinkable tubing construction. More particularly, the disclosed invention relates to a heat-shrinkable tubing jacket or jacket assembly having a tear member extruded therein for enabling users thereof to tear through the wall of the jacket assembly to enable tubing or jacket release from an underlying substrate.

2. Description of the Prior Art

U.S. Pat. No. 4,138,457 ('457 Patent), which issued to Rudd et al., discloses a Method of Making a Plastic Tube with Plural Lumens. The '457 Patent teaches a plastic tube having a main lumen, an auxiliary lumen, and an integral connector at one end for connecting the main lumen in fluid communication with another device. The auxiliary lumen extends longitudinally within the side wall of the tube with the integral tube connector free of the auxiliary lumen. The tube can be made by extruding thermoplastic material through a die having a hollow main lumen die pin and a hollow auxiliary lumen die pin adjacent the die outlet orifice. Air under pressure is supplied to both die pins to produce tubing extrudate having main and auxiliary lumens. The pressure of the air supplied to the auxiliary lumen forming pin is reduced at programmed intervals during the extrusion of the tubing so that selected portions are free of an auxiliary lumen or have a lumen of limited size. The tubing can be severed so that it has a selected portion at one end that can serve as an end connector.

U.S. Pat. No. 5,226,899 ('899 Patent), which issued to Lee et al., discloses a Catheter Tubing of Controlled in Vivo Softening. The '899 Patent teaches a catheter tubing having a layer of a hydrophobic stiffening polymer encapsulated by a layer of hydrophilic thermoplastic base polymer. Preferred stiffening polymers are polyesterpolyether block copolymers. Preferred base polymers are thermoplastic polyetherurethanes. The encapsulated layer may be a stripe or an annular layer having base polymer layers laminated on both surfaces thereof.

U.S. Pat. No. 5,246,452 ('452 Patent), which issued to Sinnott., discloses a Vascular Graft with Removable Sheath. The '452 Patent teaches a porous graft having a non-porous coating or sheath which does not adhere to the graft. After the graft is implanted into the patient, circulation is restored through the graft. The sheath is left in place temporarily while blood works its way through the wall of the porous graft to the non-porous sheath, where it is prevented from leaking. Clots form in the graft, sealing it. After a few minutes, the sheath is removed. The graft or the inside surface of the sheath can be pre-treated with a coagulant to accelerate clotting. The sheath is applied to the graft as a coating, e.g. by dipping or spraying, or as a separate sleeve, e.g. heat-shrinkable tubing. The sheath can be removed by cutting. Preferably, the sheath incorporates a string, strip, or ribbon of material which is attached to the sheath. For removal, the string is pulled, tearing the sheath which is removed with the string.

U.S. Pat. No. 6,206,430 ('430 Patent), which issued to Pond et al., discloses a Connector and Attachment Mechanism for a Lumen. The '430 Patent teaches a fitting and attachment assembly including a connector having a conventional proximal end and a distal end having a barbed portion thereon; said distal end being mateable with fluid delivery tubing. The mating end portion of said tubing including a separable annular collar in abutting relationship with the end of said tubing and a severable heat-shrinkable sleeve positioned externally of said tubing. A mechanism is further provided for severing said sleeve.

U.S. Pat. No. 6,938,645 ('645 Patent), which issued to Duarte et al., discloses a Protective Sheath having a Longitudinal Strip made of Flexible Material, and Method of Manufacturing such a Sheath. The '645 Patent teaches an annulated tubular sheath having a split down a longitudinal section thereof. According to the invention, a longitudinal strip of the sleeve is made of a flexible material and is disposed in an angular position of 5-180 degrees in relation to the longitudinal section or is disposed in the region of the sheath in which the longitudinal section is made. Preferably, the flexible material is a thermoplastic elastomer. The invention also relates to a method for producing a sleeve by extruding a plastic material, a longitudinal strip made of a flexible material obtained by co-extruding an elastomer material. A device for carrying out said method comprises an extrusion head provided with an insert for placing the co-extrusion in a stop position on a die in order to block the flow of the extruded plastic material and to enable the flow of elastomer material.

U.S. Pat. No. 6,976,991 ('991 Patent), which issued to Hebert et al., discloses a Manipulatable Delivery Catheter for Occlusive Devices. The '991 Patent teaches a delivery catheter with a flexible, proximally-manipulated hinge or joint region. The inventive catheter may have a balloon region. The catheter may have a shaft of varying flexibility which contains several lumens. The inner, or delivery, lumen generally may be used with a guide wire to access target sites within the body via the flexible, small diameter vessels of the body. The delivery lumen may be also used for placement of occlusive materials, e.g., in an aneurysm. Inflation of the micro-balloon, located near the distal tip of the catheter, is effected using the inflation lumen. The push/pull wire lumen contains a wire, which when manipulated, flexes the catheter's distal tip. The push/pull wire tubing may have a variable thickness to aid in adjusting the degree of flexibility. Moreover, the delivery catheter may be capable of twisting in a helical or corkscrew-like manner for traversing certain vasculature. This may be accomplished by winding the push/pull wire within the catheter and fixedly attaching it. The catheter may further include an entry in the catheter wall to allow for the insertion of a guide wire; this may facilitate the rapid exchange of catheter devices as desired by the user.

United States Patent Application Publication No. 2005/0165366, authored by Brustad et al., teaches a medical tubing adapted for insertion into a body tissue or cavity and method of manufacturing different variations of the tubing along a length of the tubing. The tubing comprises a plurality of individual, discrete, generally ring-shaped elements arranged in series and fused or bonded together forming a continuous tubular structure. The ring-shaped elements may be formed of a thermoplastic or a thermoset material. The ring-shaped elements may include plastic rings, metallic rings, un-reinforced plastic rings and/or metal reinforced plastic rings assembled along the length of the tubular structure to provide variable flexibility and kink-resistance. The tubular structure may have a cross-section of any geometric shape and it may be bent, twisted or curved without kinking. The ring-shaped elements may have different flexural modulus. The ring-shaped elements may include a combination of flexible and rigid ring-shaped elements assembled along different portions or sections of the tubular structure. The ring-shaped elements may be metallic and may be bonded with a resilient, flexible elastomeric adhesive, wherein the ring-shaped elements may have different lengths and may be fused closer or further apart to one another depending on the characteristics of a portion or section of the tubing. In another aspect of the invention, the medical tubing may further comprise a secondary lumen and a pull wire to control the tubular structure. The ring-shaped elements may be truncated to provide a bending bias. In another aspect of the invention, the ring-shaped elements may vary in diameter and/or composition in different portions or sections of the tubular structure. In yet another aspect of the invention, some of the ring-shaped elements may be radiopaque, or the ring-shaped elements may comprise of different colors to operate as indicators along the tubular structure.

Arguably, the most pertinent of the foregoing disclosures includes the '452 Patent and the '430 Patent. From an inspection of the '452 Patent, it will be seen that the disclosed product is a vascular graft with removable sheath. It will be further seen that the outer sheath is optionally a heat-shrinkable coating or sleeve, incorporating a string, strip, or ribbon of material thereunder, which tear member is notably under the sheath, not incorporated or extruded into the sheath. The purpose for the tubing of the '452 Patent is thus different than the purpose or object of the present tubing construction. Notably, the pullable member of the '452 Patent is laid underneath the outer tubing directly contacting the underlying substrate such as graft 10. Direct contact with the underlying substrate, such as graft 10, oftentimes results in damage to the substrate. Thus, the prior art perceived a need for a heat-shrinkable tubing having a tear member extruded within the wall of the outer sheath (i.e. intermediate the inner and outer diameter of the outer sheath) for enabling removal thereof.

With regard to the '643 Patent, it will be seen that the tear member is also situated in contacting superficial adjacency to the inner substrate such as inner tubing 40. Situating the tear member under (i.e. not within) the outer heat-shrinkable tubing, while perhaps providing a superior sheath removal mechanism, also promotes damage of the underlying substrate. Given the highly sensitive nature of medical applications in which the constructions of the '452 and '643 Patent(s), it is preferably to provide a tubing construction comprising an outer heat-shrinkable tubing with a tear member extruded intermediate the inner and outer diameters so as to enable sheath removal, while protecting the underlying substrate from damage.

For medical applications, such as catheter applications, it is noted that oftentimes these devices typically comprise several tubular layers of material, one over the other. A heat shrink tubing is often utilized as a last step in the manufacture or as the outermost sheath or layer. Often this tubing is FEP/Teflon tubing but it could also be other materials. When this material is shrunk over the underlying substrate(s), it causes the layer immediately under it to melt and flow into the layers below and to cause those layers to all meld or bond together. The final step, then, involves stripping off that heat shrink tubing layer and throwing it away. In this application the heat shrink tubing is essentially being used as a tool or mechanical device. The current /common method for removal (in devices not incorporating a tear member) is to take a razor or sharp type of tool and to drag the tool along the length of the device with the goal being to “score” the shrink tubing or to cut part way through the wall. Ideally they try to cut most of the way through the wall so that after the scoring is done, on one or more sides, the heat shrink tubing can be easily peeled away.

SUMMARY OF THE INVENTION

Accordingly, in an attempt to address the foregoing shortcomings readily apparent in the prior art, the disclosed thermoplastic tubing construction shrink tubing jacket assembly essentially provides certain heat shrinkable tubing with a wire or other tear member device built or extruded “into the wall” of the tubing. Similar to state of the art garden hoses and the like, which incorporate braided textile material into the tubing, the tear member is not exposed at either the inner or outer diameter of the tubing construction, but rather embedded within the wall structure of the tubing.

For non medical applications, such as covering various rollers, parts or other structures, this tubing can be used allowing for ease of tubing or sheath removal at the user's election. Further, in electrical applications, when conductors may be covered with insulation to protect or insulate the underlying conductor(s), and sheath removal may be required, the essence of the present invention may be effectively practiced.

The method of sheath removal inherently taught by the present invention is necessarily less “craft sensitive” than those tubing constructions requiring lengthwise cutting to remove an outer sheath. Inexperienced practitioners may well be able to remove the sheaths, having been shown, where to pull. Further, there is little chance of damaging the underlying substrate as, for example, by cutting too deep.

In practice, the user may simply trim the ends of the tubing to expose the tear member at both ends. After fixing one end thereof (i.e. by clamping same), the other (free) end may be pulled, outward (thereby slicing through the tubing wall) and toward the first fixed end. The final removal is made easy by simply pulling at the tubing and the tubing will tear in the region where new weak structural lines have been created (i.e. that region directly underlying the extrusion zone essentially forming a thin easily penetrable or tearable membrane). In this last regard, it should be noted that the wire or tear member is extruded closer to the inner wall than the outer wall as the desire is to tear as much wall material as possible during the wire pulling process. Ideally this wire or tear member would be embedded in radial outward adjacency to the inner wall or diameter of the tubing.

Notably, the end product on which the tubing construction of the present invention is to be used, (for example, a catheter being manufactured) will not differ as practiced under the currently disclosed structure(s) and method(s). The resultant end product will be the same. Foreseeable benefits of the tubing construction herein contemplated include enhanced ease and speed of manufacture, as well as a lessened scrap rate of relatively expensive base component materials. Perhaps most notably, however, is a decrease in stress and strain on the end product resulting in higher end product reliability. It is further believed that commonly used scoring techniques have limitations in terms of the sizes of products with which they will work. In this regard, it is noted that as catheters and the like become smaller in diameter it becomes more and more difficult to properly score or scribe a partial cut line along their surface. The construction of the present invention may well be incorporated into almost any size of heat shrink tubing, thus obviating the obstacle of difficult, small-diameter tubing.

Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated or become apparent from, the following description and the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features of my invention will become more evident from a consideration of the following brief description of patent drawings:

FIG. 1 is a transverse cross-sectional type depiction of a first preferred embodiment of the shrink tubing jacket construction of the present invention showing a single tear member.

FIG. 2 is a transverse cross-sectional type depiction of a second preferred embodiment of the shrink tubing jacket construction of the present invention showing opposing tear members.

FIG. 3 is a transverse cross-sectional type depiction of a first alternative embodiment of the shrink tubing jacket construction of the present invention showing a single member-receiving lumen.

FIG. 4 is a transverse cross-sectional type depiction of a second alternative embodiment of the shrink tubing jacket construction of the present invention showing opposing member-receiving lumens.

FIG. 5 is a lateral view type depiction of the second preferred embodiment of the shrink tubing jacket construction of the present invention with end portions broken to show the opposing tear members.

FIG. 6 is an edge view type depiction of a pulley system for mechanized tear member removal from the shrink tubing jacket construction of the present invention.

FIG. 7 is a plan view type depiction of the pulley system otherwise depicted in FIG. 6 for mechanized tear member removal and shrink tubing jacket construction according to the present invention.

FIG. 8 is a plan view type depiction of the pulley system otherwise depicted in FIG. 7 removing tear members from the shrink tubing jacket construction of the present invention.

FIG. 9 is a first longitudinal type depiction of a shrink tubing jacket construction having a translucent tubing structure so as to enable the user to visually perceive the tear member embedded within the wall thereof.

FIG. 10 is a second longitudinal type depiction of a shrink tubing jacket construction having trimmed ends so as to expose ends of the tear member.

FIG. 11 is a third longitudinal type depiction of a shrink tubing jacket construction having scored sections or pre-scored ends so that the tear member ends may be more easily accessed by manually ripping the tubing at the scoring.

FIG. 12 is a transverse cross-sectional type depiction of a first embodiment of a single slotted jig formed of relatively rigid material for enveloping the shrink tubing jacket construction for aiding tear member removal (via the slotted portion).

FIG. 13 is a transverse cross-sectional type depiction of the slotted jig otherwise depicted in FIG. 12 enveloping the first preferred embodiment of the shrink tubing jacket construction of the present invention, which jacket construction is sheath-enveloping a catheter.

FIG. 14 is a transverse cross-sectional type depiction of a second embodiment of a dual-slotted jig formed of relatively rigid material for enveloping the shrink tubing jacket construction for aiding tear member removal (via the slotted portions).

FIG. 15 is a transverse cross-sectional type depiction of a prior art type substrate with a tear member interstitially sandwiched between the substrate and a shrinkable tubing jacket.

FIG. 16 is a transverse cross-sectional type depiction of a prior art type jacketed catheter (with underlying substrate) with a tear member interstitially sandwiched between the catheter and a shrinkable tubing jacket.

FIG. 17 is a transverse cross-sectional type depiction of a prior art type catheter (with underlying substrate) with a groove or slot formed therein via heat shrinking action of the shrinkable tubing jacket otherwise removed from the figure.

FIG. 18 is a transverse cross-sectional type depiction of an arc length of tubing material.

FIG. 19 is a transverse cross-sectional type depiction of a partially disassembled preliminary shrink tubing jacket construction showing a tubing construction, a tear member in radially inward adjacency thereto.

FIG. 20 is a transverse cross-sectional type depiction of the shrink tubing jacket construction otherwise shown in FIG. 19 in assembled relation with the arc length of tubing shown in FIG. 18.

FIG. 21 is a transverse cross-sectional type depiction of the assembled shrink tubing jacket otherwise shown in FIG. 20 enveloping an underlying substrate in a pre-shrink state.

FIG. 22 is a transverse cross-sectional type depiction of the structures otherwise depicted in FIG. 21 in a post-shrink state.

FIG. 23 is a transverse cross-sectional type depiction of a heat shrinkable tubing construction with a lumen formed in the wall thereof.

FIG. 24 is a transverse cross-sectional type depiction of a further alternative assembly of the present invention comprising an inner slotted sleeve, and an outer shrink tubing jacket construction.

FIG. 25 is a fragmentary perspective type depiction of a shaft with an outer shrink tubing jacket layer with a tear member inserted into the wall of the tubing jacket layer.

FIG. 26 is a fragmentary perspective type depiction of the assembly otherwise depicted in FIG. 25 wherein the tear member-bearing wall has a tear-through started as enabled via the tear member.

FIG. 27 is a fragmentary longitudinal or side type view of the assembly otherwise depicted in FIG. 26 wherein the tear member of the tear member-bearing wall is pulled or torn through a majority of the tubing length.

FIG. 28 is a fragmentary longitudinal or side type view of the assembly otherwise depicted in FIG. 27 wherein the tear member of the tear member-bearing wall is pulled or torn through the full tubing length.

FIG. 29 is a fragmentary side view type depiction of a first end of a common guiding catheter type construction outfitted with a shrink tubing jacket outer layer and guiding an inner form-easing mandrel.

FIG. 30 is a fragmentary side view type depiction of a common guiding catheter type construction otherwise depicted in FIG. 29 comprising inner and outer tubing layers with a braided interstitial layer between the inner and outer tubing layers.

FIG. 31 is an expanded fragmentary side view type depiction of the structures otherwise depicted in FIG. 29 showing the multi-layered assembly from two ends.

FIG. 32 is a fragmentary side view type depiction of a shaft type member with a shrink tubing jacket construction outer layer and an inner mandrel.

FIG. 33 is a fragmentary side view type depiction of a group of conductor members with an outer layer defined by a shrink tubing jacket construction of the present invention.

FIG. 34 is a fragmentary side view type depiction of an underlying substrate with a shrink tubing jacket construction as a partial outer layer with a tear member extending from one end thereof and as positioned adjacent a U.S. coin for sizing perspective.

FIG. 35 is a first sequential, fragmentary perspective type depiction of a shaft outfitted with a shrink tubing jacket construction of the present invention wherein the tear member of the tear member-bearing wall is pulled or torn through a majority of the tubing length.

FIG. 36 is a second sequential, fragmentary perspective type depiction of structures otherwise depicted in FIG. 35 wherein the tear member of the tear member-bearing wall is nearly pulled or torn through the entire tubing length.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings, a first preferred embodiment of the present invention concerns a shrink tubing jacket construction 10 as generally illustrated and referenced in FIGS. 2, 5, 7, 8, and 9-11. Further depictions of the shrink tubing jacket construction 10 are shown in FIGS. 4( a)-6(b). A second preferred embodiment of the shrink tubing jacket construction 10(a) is depicted and referenced in FIGS. 1, 13, 32, 33, 35, and 36. It will be seen from an inspection of the noted figures that the primary difference between the first preferred shrink tubing jacket construction 10 and the second preferred shrink tubing jacket construction 10(a) is the extrusion of two wires, monofilaments, or other tear members 11 (in the first preferred embodiment) into the wall 12 of heat shrink tubing 13 as compared to the extrusion of a single wire, monofilament, or other tear member 11 into the wall 12 of certain heat shrink tubing 13 (in the second preferred embodiment).

In the preferred embodiment, two tear members 11 are situated 180 degrees from one another or along a common diameter at opposite sides of tubing 13. Certain tear members 11 are illustrated and referenced in FIGS. 1, 2, 5, 8, 9-11, 15, 16, 19, 20, 21-28, and 32-36; wall 12 is illustrated and referenced in FIGS. 1-5, 13, 15, 16, 19, and 20-22; and tubing 13 is illustrated and referenced in FIGS. 1-5, 7-11, 15, 16, 19-23, 25-29, and 31-36. It is further contemplated that the teachings of the present disclosure present a certain novel method of removing heat shrink tubing 13 from an underlying substrate, such as a catheter 14, which catheter or catheter construction 14 is generally illustrated and referenced in FIGS. 13, 16, 17, 21, 22, and 29-31. Other underlying substrates may include a shaft, roller or other similar component 15 as illustrated and referenced in FIGS. 25-28, and 34-36; or a bundle of conductors or wires (to form a cable) as at 16 and illustrated and referenced in FIG. 33. In this last regard, it is contemplated that ripping radially outward and lengthwise through an outer shrink tubing jacket layer in order to remove the same from an underlying substrate is novel methodology in the art.

It will be understood from an inspection of the noted or applicable figures, that the tear member(s) 11 are preferably extruded or embedded within the wall 12 as close to the inner diameter (as at 17) as possible so that the tear member 11 removal (as generally depicted in FIGS. 8, 25-28, and 34-36)) will tear or cut through as much wall 12 as possible making full removal of the tubing 13 as easy as possible due to minimal remaining material (in radially inward adjacency to tear member(s) 11 as referenced at 18 in FIG. 1 to tear or remove. It is contemplated that material 18 may be easily broken or torn (i.e. manually rupturable), the same essentially being a minimized material membrane extending intermediate the extruded tear member 11 and the inner diameter 17 of the tubing 13.

Further, it may be readily understood that that shrink tubing jacket construction 10 preferably comprises two or paired tear members 11 (each pair being 180 degrees apart). In this regard, it is contemplated that dual or paired wires or tear members 11 may be pulled in radially opposite directions so as to input less bending stress on the substrate and also to make final tearing of the tubing 13 easier. In other words, it is contemplated that paired tear members 11 lying along a common diameter on opposite sides of tubing 13 may well function to prevent undue bending of the underlying substrate. In this regard, it is contemplated that wire removal may be effected by a mechanized dual pulley system as generally depicted in FIGS. 6-8, which pulley system may well function to impart equal and opposite tensile forces upon the tear members 11 for effecting a zero net bending force on the underlying substrate to which the construction 10 is attached.

From an inspection of FIG. 8, for example, it will be seen that when two or paired tear members 11 are incorporated into the design and harnessed to paired pulley assemblies 20, the tear members 11 may be effectively engaged and pulled at common pull rates with common tensile force. In other words, it is contemplated that the assemblies 20 preferably function to rotate at a common velocity in opposite directions for pulling the tear members 11 radially outward from the relaxed, extruded position (as generally depicted in FIG. 5), thereby imposing material-tearing forces (as imparted by pulley assemblies 20 and the inherent tensile strength of the tear members 11), the material-tearing forces essentially operating to impart substantially equalized forces as at vector arrows 21 in FIG. 8, thereby resulting in reduced stress on the underlying substrate. In other words, the net force on the substrate would tend toward zero resulting in reduced stress and strain. Notably, it is further contemplated that the mechanized “ripping speed” can be relatively slow for controlled jacket removals or spring-loaded for effecting rapid, distortion-minimizing jacket removals.

From an inspection of FIGS. 3, 4, and 23, it may be further understood that a certain tear member-receiving lumen 22 (or lumens 22) may be incorporated into the wall 12 of the tubing 13 of the present invention. A fine wire or tear member 11 could be fed through or received by the lumen 22, which tear member 11, after being inserted into or received by the lumen 22, may well function to enable the user to tear through wall 12 of tubing 13 for tubing or jacket removal as generally depicted throughout the applicable figures. In this regard, it is contemplated that a lumen 22 may be formed in the wall 12 if extrusion or embedded placement of a wire or tear member 11 is not possible given material requirements. Notably, the lumen 22 could fulfill other useful purposes, as may be gleaned from a general consideration of the state of the art.

From an inspection of FIGS. 9-11, it may be noted that certain means for accessing the tear member 11 are contemplated. In this regard, it is contemplated that said means may, in a first scenario, be defined by the translucent material construction of the tubing 13. In other words, it is contemplated that the tubing structure 13 may be constructed from translucent material(s) so as to enable the user to visually perceive the tear member 11 embedded within the wall 12 as generally depicted in all three figures. Other means for accessing the tear member 11 may be defined by exposed end(s) 23 of a tear member 11. In this regard, it is contemplated that the ends 23 of tubing 13 may be trimmed away thereby exposing ends 23 as generally depicted in FIG. 10. Further, the ends 23 of tubing 13 may be pre-scored as at 24 in FIG. 11 so that tear member ends 23 may be more easily accessed by manually ripping tubing 13 at said scoring 24.

From an inspection of FIGS. 7( a) and 7(b), it will be seen that other means for facilitating tubing removal may be utilized in combination with tear member(s) 11, which means may be defined by certain fixtures or jigs which function to provide shaft support (and are thus preferably constructed from relatively rigid materials) during tear member action. In this regard, it is contemplated that slit metal or plastic tubing 25 may envelope shrink tubing jacket constructions 10 or 10(a). It is contemplated that the tubing may well function to facilitate removal of the tear member 11 without bending or otherwise straining the underlying substrate (e.g. a catheter 14). The underlying substrate or catheter 14 could be placed inside such tubing 25 (sized for the application) so that the tear member 11 is positioned in radial inward adjacency to one or more slots 26 as further generally depicted and referenced. Tear member 11 may then be pulled radially outward through the slot 26 and then pulled, upward or against the grain, toward the opposite end of tubing 13. Notably, this process can be performed in a heated environment which eases the tearing and slitting of the tubing 13 (optionally constructed from FEP heat shrink type thermoplastic).

From an inspection of FIGS. 15 and 16, it may be seen that certain prior art methodology has included attempts to overlay a tear member 11 in contact with an underlying substrate (i.e. the tear member 11 not being embedded in the wall 12 of tubing 13). In other words, prior art tear members 11 have been loosely sandwiched or interstitially situated intermediate the underlying substrate 27 and the tubing 13 as generally depicted in FIG. 15. While it is noted that this type of prior art tear member 11 may effectively function to tear through the overlying tubing 13 (whether in a heated or chilled state), it is further noted that when heated and driven against the outer diameter 28 of the underlying substrate 27 (such as a catheter 14), the tear member 11 often causes a problematic longitudinal groove 29 to form in the outer diameter 28 as generally depicted in FIG. 17.

In this last regard, it should perhaps be further noted that if the underlying substrate 27 is relatively thin thermoplastic on a mandrel, the heated tear member 11 may cut through the outer diameter 28 underlying substrate 27. Test results have suggested the preferred manufacture of the removal jacket construction of the present invention, the same being to embed or extrude the tear member 11 within wall 12 so as to prevent direct contact intermediate the tear member(s) 11 and the underlying substrate 27.

As earlier stated, and as further supported in FIG. 32, heat shrink tubing 13 is often used as a temporary covering or protective layer for a shaft, roller or other similar component 15. Such tubing is often stripped off with a razor type cutting implement. However, if underlying surface damage is to be avoided, (e.g. for corrosion protection), an easily strippable jacket construction such as construction 10 or 10(a) as taught by the present invention may be effectively utilized. From an inspection of FIG. 33, it may be further noted that heat shrink tubing 13 is also often used to cover a group of conductors 16 to form the same into a cable or to jacket and sheath-protect them. If damage occurs or if an individual conductor 16 fails, or if added circuits become required, it may become necessary to remove the jacket or outer sheath. It may be difficult to remove the outer jacket with a cutting implement such as a razor or knife. Having a tear member 11 in the outer tubing 13 makes outer sheath or jacket removal easy and greatly reduces the chances of damaging the underlying conductors 16.

As has been noted hereinabove, current and common methods for removing shrink tubing jackets, and other plastic layers, include scoring methods or mechanisms with certain depth control of the scoring blade or blades. In the case of an underlying catheter type substrate, it is common to make two score lines, lengthwise, scoring most of the way through the outer shrink layer, normally the two score lines being 180 degrees opposed or on opposite sides of the shaft. This allows the tearing process to easily peel away with the material giving way at the weakened score line. Pitfalls, however, are experienced with this type of scoring method including extreme difficulty with effectively accomplishing the task on relatively small diameter shafts. Further, as walls become thinner it is difficult to control a partial score in the wall without cutting through the wall and damaging the substrate underneath. Wall thickness, thus, should be consistent for this state of the art methodology to be effective; if the substrate varies in diameter then the shrink tubing layer will have a graduated thickness, making a depth set blade less effective.

A buried “zip wire” or tear member 11, however, has proven effective in outer heat shrink tubing jacket removal. The removal of an outer tubing sheath and the like is clean and tends to prevent damage to the underlying substrate. To prevent the wire or tear member 11 from being pulled into the lumen when pulled from the opposite end, the wire can be grabbed, fixtured, or attached which will ensure the ability to pull with sufficient force to rip through the tubing wall 12. Wall thickness can also be varied, possibly adding thickness to the lumen areas to compensate for the lessened material due to the lumen.

While the above description contains much specificity, this specificity should not be construed as limitations on the scope of the invention, but rather as an exemplification of the invention. For example, as is described hereinabove, it is contemplated that the present invention essentially discloses a shrink tubing jacket construction for enabling blade-free removal of shrink tubing from an underlying substrate. The shrink tubing jacket construction according to the present invention may be said to comprise an axial length of shrink tubing and an axial length of zip wire or similar tear member. The shrink tubing has an inner tubing diameter, an outer tubing diameter, a tubing length, a tubing wall, and an axial lumen, which lumen functions to receive the tear member.

The tubing wall is bound by the inner and outer tubing diameters as well as the tubing length. The tubing wall has a certain tubing material strength. The inner tubing diameter functions to receiving an underlying substrate and the axial lumen extends through the tubing wall intermediate the inner and outer tubing diameters. Notably, the axial lumen has a lumen length at least equal to the tubing length. The tear member is insertable through the lumen thereby being received within the tubing wall.

The tear member has a member length and a member material strength. The member length has a magnitude at least equal to the lumen length, and the member material strength is greater in magnitude than the tubing material strength such that when the tear member is tensioned in a diametrical direction relative to the shrink tubing, the tear member is able to slice through the axial lumen and tubing wall toward a select tubing diameter, which may be preferably defined by the outer tubing diameter.

The lumen may be preferably formed in the tubing wall relatively closer to the inner tubing diameter as compared to the outer tubing diameter such that when the tear member is directed toward the outer tubing diameter, a minimized material membrane is left behind adjacent the inner tubing diameter as a result of the slicing action. The minimized material membrane is manually rupturable for manually removing the shrink tubing from the underlying substrate.

The shrink tubing jacket construction may comprise a second axial lumen substantially identical to the first axial lumen, but diametrically opposed thereto, and a second tear member substantially identical to the first tear member may be inserted into the second lumen. The first and second tear members may well cooperate to slice through the first and second lumens and the tubing wall in diametrically opposite directions. In this regard, it is contemplated that the first and second tear members are collinearly tensionable as generally depicted in FIG. 8 with substantially equal tension for reducing the net stress on the underlying substrate.

Further means for reducing the net stress on the underlying substrate may be defined by a slotted jig, which slotted jig is preferably constructed from a substantially rigid material and essentially comprises a lengthwise slot and an inner jig diameter. The inner jig diameter is greater in magnitude than the outer tubing diameter for receiving the shrink tubing. The slot may be oriented in radially outward adjacency to the lumen(s) and tear member(s) such that when tensioned in a diametrical direction, the tear member may be guided through the slot. It is contemplated that the rigid material of the slotted jig may well function to reduce the net stress and bending strain on the underlying substrate as the tear member slices through the tubing wall.

Stated another way, the shrink tubing jacket construction may be said to essentially comprise certain shrink tubing and with an embedded or wall-located tear member. The shrink tubing has an inner tubing diameter, an outer tubing diameter, a tubing length and a tubing wall, which wall has a tubing material strength. The inner tubing diameter functions to receive some type of underlying substrate as specified hereinabove. The tear member is embedded in the tubing wall and preferably has a member length and a member material strength, which member length has a magnitude at least equal to the tubing length, and which member material strength is greater in magnitude than the tubing material strength such that when the tear member is tensioned in a diametrical direction relative to the shrink tubing, the tear member may well slice through the tubing wall.

In addition to the novel jacket construction, the foregoing specifications are thought to further support certain novel methodologies, including a method for outfitting a shrink jacket upon, and removing a shrink jacket from, an underlying substrate; as well as certain method of manufacture. The method for outfitting a substrate and removing the outfit from the substrate may be said to essentially comprise the steps of locating a tear member intermediate an inner and outer tubing diameter along a length of shrink tubing at a sheath slicing depth as generally depicted in the noted figures. The sheath-slicing depth may be defined by the distance intermediate the member 11 and the outer diameter of the tubing 13. After so locating the tear member, an underlying substrate may be received within the inner tubing diameter whereafter the inner tubing diameter may be reduced (as, for example, by applying heat and heat-shrinking the tubing 13). This latter action may well function to sheath-protect the underlying substrate.

When the user wishes to remove the sheath-protecting outer shrink rubbing jacket construction, as exemplified by the foregoing, the tear member may be tensioned in a diametrical direction relative to the length of shrink tubing, which action may well function to slicing through the shrink tubing from the sheath-slicing depth toward a select tubing diameter, which select tubing diameter may be typically defined by the outer tubing diameter for removing the shrink tubing jacket construction from the underlying substrate.

The method may comprise certain additional steps including forming a member-receiving lumen intermediate the inner and outer tubing diameter through the length of shrink tubing at a sheath-slicing depth and then inserting the first tear member in the member-receiving lumen. Further, the step of locating the first tear member may be defined by locating the tear member within the tubing wall relatively closer to the inner tubing diameter as compared to the outer tubing diameter. As earlier stated, the tear member may then be directed toward the outer tubing diameter during the step of tensioning the tear member for leaving a minimized material membrane adjacent the inner tubing diameter. The minimized material membrane is thought to be manually rupturable for enabling manual removal the shrink tubing from the underlying substrate.

Certain methods for minimizing the stress/strain on the underlying substrate include locating a second tear member diametrically opposed to the first tear member intermediate the inner and outer tubing diameters through the length of shrink tubing at the sheath-slicing depth. The first and second tear members are collinearly tensionable for slicing through the shrink tubing for reducing the stress/strain on the underlying substrate. Further, the shrink tubing may be jig-enveloped before or while slicing through the shrink tubing. It is contemplated that the jig-enveloped shrink tubing may well function to guide the slicing action while also minimizing stress and strain on the underlying substrate.

Although the invention has been described by reference to a number of preferred and alternative embodiments, as well as a number of different methods, it is not intended that the novel devices and methods be limited thereby, but that modifications thereof are intended to be included as falling within the broad scope and spirit of the foregoing disclosure and the appended drawings. 

1. A shrink tubing jacket construction for enabling blade-free removal of shrink tubing from an underlying substrate, the shrink tubing jacket construction comprising: an axial length of shrink tubing, the shrink tubing having an inner tubing diameter, an outer tubing diameter, a tubing length, a tubing wall, and a first lumen, the tubing wall being bound by the inner and outer tubing diameters and the tubing length, the tubing wall having a tubing material strength, the inner tubing diameter for receiving the underlying substrate, the first lumen extending through the tubing wall intermediate the inner and outer tubing diameters, the first lumen having a lumen length at least equal to the tubing length; and a first tear member, the first tear member being insertable through the First lumen thereby being received within the tubing wall, the first tear member having a member length and a member material strength, the member length having a magnitude at least equal to the lumen length, the member material strength being greater in magnitude than the tubing material strength such that when the first tear member is tensioned in a diametrical direction relative to the shrink tubing, the first tear member slices through the first lumen and tubing wall toward a select tubing diameter.
 2. The shrink tubing jacket construction of claim 1 wherein the first lumen is formed in the tubing wall closer to the inner tubing diameter relative to the outer tubing diameter, the first tear member being diametrically directed toward the outer tubing diameter during slicing action thereby leaving a minimized material membrane adjacent the inner tubing diameter, the minimized material membrane being manually rupturable for manually removing the shrink tubing from the underlying substrate.
 3. The shrink tubing jacket construction of claim 1 comprising a second lumen substantially identical to the first lumen, and a second tear member substantially identical to the first tear member, the second lumen being diametrically opposed to the first lumen, the second tear member being insertable through the second lumen, the first and second tear members for slicing through the first and second lumens and the tubing wall in diametrically opposite directions.
 4. The shrink tubing jacket construction of claim 3 wherein the first and second tear members are collinearly tensionable with substantially equal tension for minimizing stress and strain on the underlying substrate during slicing action.
 5. The shrink tubing jacket construction of claim 1 comprising a slotted jig, the slotted jig being constructed from a substantially rigid material and comprising a slot and an inner jig diameter, the inner jig diameter being greater in magnitude than the outer tubing diameter for receiving the shrink tubing, the slot being orientable in radially outward adjacency to the first lumen, the first tear member being tensioned in a diametrical direction through the slot, the rigid material of the slotted jig for minimizing stress and strain on the underlying substrate during slicing action.
 6. The shrink tubing jacket construction of claim 1 comprising tear member-accessing means for enabling a user to more easily access the tear member.
 7. A shrink tubing jacket construction for enhancing removal of shrink tubing from an underlying substrate, the shrink tubing jacket construction comprising: shrink tubing, the shrink tubing having an inner tubing diameter, an outer tubing diameter, and a tubing wall, the tubing wall having a tubing material strength, the inner tubing diameter for receiving the underlying substrate; and a first tear member, the first tear member being located in the tubing wall, the first tear member having a member material strength, the member material strength being greater in magnitude than the tubing material strength such that when the first tear member is tensioned in a diametrical direction relative to the shrink tubing, the first tear member slices through the tubing wall toward a select tubing diameter.
 8. The shrink tubing jacket construction of claim 7 wherein the first tear member is located in the tubing wall in closer proximity to the inner tubing diameter relative to the outer tubing diameter, the first tear member being directed toward the outer tubing diameter during slicing action thereby leaving a minimized material membrane adjacent the inner tubing diameter, the minimized material membrane being manually rupturable for manually removing the shrink tubing from the underlying substrate.
 9. The shrink tubing jacket construction of claim 7 comprising a second tear member, the second tear member being opposed to the first tear member, the first and second tear members for slicing through the tubing wall in diametrically opposite directions.
 10. The shrink tubing jacket construction of claim 9 wherein the first and second tear members are collinearly tensionable for minimizing stress and strain on the underlying substrate during slicing action.
 11. The shrink tubing jacket construction of claim 7 comprising a slotted jig, the slotted jig being constructed from a substantially rigid material and comprising a slot and an inner jig diameter, the inner jig diameter being greater in magnitude than the outer tubing diameter for receiving the shrink tubing, the slot being orientable in adjacency to the first tear member, the first tear member being tensioned in a diametrical direction through the slot, the rigid material of the slotted jig for minimizing stress and strain on the underlying substrate during slicing action.
 12. The shrink tubing jacket construction of claim 7 comprising tear member-accessing means for enabling a user to more easily access the tear member.
 13. A tear-removable jacket for enhancing removal of sheath-protecting tubing from an underlying substrate, the jacket comprising: tubing material, the tubing material having an inner tubing diameter, an outer tubing diameter, and a tubing wall, the tubing wall having a tubing material strength, the inner tubing diameter for sheath-protecting the underlying substrate; and a tear member, the tear member being extruded into the tubing wall, the tear member having a member material strength, the member material strength being greater in magnitude than the tubing material strength such that when the tear member is tensioned in a diametrical direction relative to the tubing material, the tear member slices through the tubing wall toward a select tubing diameter.
 14. The tear-removable jacket of claim 13 wherein the tear member is located in the tubing wall in closer proximity to the inner tubing diameter relative to the outer tubing diameter, the tear member being directed toward the outer tubing diameter during slicing action thereby leaving a minimized material membrane adjacent the inner tubing diameter, the minimized material membrane being manually rupturable for manually removing the jacket from the underlying substrate.
 15. The tear-removable jacket of claim 13 comprising two tear members, the two tear members being diametrically opposed for slicing through the tubing wall in diametrically opposite directions.
 16. The tear-removable jacket of claim 15wherein the two tear members are collinearly tensionable for minimizing stress and strain on the underlying substrate during slicing action.
 17. The tear removable jacket of claim 13 usable in combination with a slotted jig, the slotted jig being constructed from a substantially rigid material and comprising a slot and an inner jig diameter, the inner jig diameter being greater in magnitude than the outer tubing diameter for receiving the tubing material, the slot being orientable in adjacency to the tear member, the tear member being tensioned in a diametrical direction through the slot, the rigid material of the slotted jig for minimizing stress and strain on the underlying substrate during slicing action.
 18. The tear-removable jacket of claim ______ comprising tear member-accessing means for enabling a user to more easily access the tear member.
 19. A method for selectively outfitting a substrate with a shrink jacket, the method comprising the steps of: locating a first tear member intermediate an inner and outer tubing diameter through a length of shrink tubing at a sheath-slicing depth; receiving an underlying substrate within the inner tubing diameter; reducing the inner tubing diameter for sheath-protecting the underlying substrate; tensioning the first tear member in a diametrical direction relative to the length of shrink tubing; and slicing through the shrink tubing from the sheath-slicing depth toward a select tubing diameter via the tensioned first tear member.
 20. The method of claim 19 wherein the step of locating the first tear member is defined by forming a member-receiving lumen intermediate the inner and outer tubing diameter through the length of shrink tubing at the sheath-slicing depth and inserting the first tear member in the member-receiving lumen.
 21. The method of claim 19 wherein the step of locating the first tear member is defined by locating the tear member closer to the inner tubing diameter relative to the outer tubing diameter, the first tear member being directed toward the outer tubing diameter during the step of tensioning the first tear member, the slicing action leaving a minimized material membrane adjacent the inner tubing diameter, the minimized material membrane being manually rupturable for manually removing the shrink tubing from the underlying substrate.
 22. The method of claim 19 wherein the step of reducing the inner tubing diameter is defined by heat-shrinking the shrink tubing.
 23. The method of claim 19 comprising the step of locating a second tear member diametrically opposed to the first tear member intermediate the inner and outer tubing diameters through the length of shrink tubing at the sheath-slicing depth, the first and second tear members being collinearly tensionable for slicing through the shrink tubing with minimized stress and strain on the underlying substrate.
 24. The method of claim 19 comprising the step of jig-enveloping the shrink tubing while slicing through the shrink tubing, the jig-enveloped shrink tubing for minimizing stress and strain on the underlying substrate. 